A medical device and method are described which provide quantitative information on the type and extent of injury to the ligaments of the ankle, elbow, knee and shoulder without the need for x-rays or other imaging modalities. The invention combines stress equipment for ligaments with electronic sensors, a computer interface and analytical software containing predictive functions to provide the care provider with an accurate diagnosis of ligament injury.
Injuries to the ligaments of the ankle and the knee have been rising sharply as our health-conscious society has taken to physical exercise and athletics. Estimates for ankle injury in the U.S suggest that as many as 10% of office and emergency room visits (approximately 20,000 ankle examinations per day or approximately 9 million per year) involve the ankle joint, of which the vast majority are lateral ankle sprains. The numbers of cruciate and collateral ligament injuries are less well known but have been increasing everywhere over the past decade. In the United States, well over 10,000 anterior cruciate ligaments are ruptured on the ski slopes alone each year. Joint injuries as a whole contribute greatly to the number of medical examinations. Although some of these injuries are mild and can be self managed following an initial diagnostic workup, they nonetheless cause significant morbidity and loss of work productivity as they affect mostly the 15- to 45-year old age group.
The initial workup of ligament injury involves, after osteochondral fractures or other complications have been excluded, an accurate assessment of the extent of ligament damage. Determining the extent of the damage to ligaments allows the physician to make the appropriate choice of treatment, including whether or not surgery is required. Equally important is monitoring the functional improvement in order to assess the success of rehabilitation programs.
The typical methods for evaluating damage to ligaments are physical examination, stress examinations including stress radiography, and occasionally magnetic resonance imaging (MRI), computerized axial tomography (CAT) scan and arthroscopy. Although MRI can directly image the affected ligament, it is unable to assess function properties. Whereas each of these diagnostic tools has its own intrinsic value, and contributes to the total assessment of the actual injury, it is evident that, together, they also markedly add to the total cost.
Current technologies for assessing joint laxity include arthrometers and goniometers and they are limited in their ease of use and diagnostic capability. A leg positioning device for taking x-rays is described in U.S. Pat. No. 4,232,681 and is one example of an early device for diagnosing ligament injury. The information contained in this patent is incorporated by reference in its entirety. This device, sold as the GA-II/E Stress Device by the Telos Corporation (Marburg, Germany) enables the examiner to position the limb and apply a measured force to the joint but requires the physician to take x-rays in order to assess the likelihood of injury to the ligament. The GA-II/E is capable of positioning multiple joints including the ankle, the knee and the shoulder for x-ray analysis of their ligaments. The positioning of the extremities to evaluate ligaments is shown in the users manuals provided by Telos Corporation and entitled Telos Stress Device Users Manual Shoulder-Positioning-Device for Standardized Axial x-rays and Stress Radiographs. These publications are incorporated by reference in their entirety. A wrist holding attachment described in U.S. Pat. Nos. 5,724,991 and 5,462,068 expands the use of the GA-II/E to the elbow. These patents are incorporated by reference in their entirety. However, this diagnostic technique is time consuming, is less reproducible, is not automated and requires the diagnostician to make measurements from the x-rays and calculate joint laxity by graphing the measured displacements.
Another technology currently in use to measure joint laxity includes the knee and shoulder testers sold by the Medmetric Corporation (San Diego, Calif.). These devices include the KT 1000 and KT 2000 knee testers and are described in U.S. Pat. Nos. 4,969,471 and 4,583,555. A shoulder tester is also described in U.S. Pat. No. 5,911,695 and a patella displacement tester is described in U.S. Pat. Nos. 5,156,163 and 6,013,039. These patents are incorporated by reference as though reproduced in their entirety. The devices described in these patents use force displacement measurements combined with linear displacement of the appropriate bones to provide diagnostic information on joint laxity. Each of these devices is limited to the assessment of the laxity of a single ligament, and therefore the purchase of multiple systemswould be required to test the various joints resulting in an increase in the cost to the physician and the patient. Further, the only information that is provided to the physician is the actual measurement of the force and the displacement, and the physician would be required to further manipulate this information in order to arrive at a diagnosis in terms of percentage tear.
Development of new technologies and approaches and/or optimization of any of the existing techniquesxe2x80x94while providing an improved, the same or at least an acceptable level of care is required to significantly reduce the cost of the diagnostic phase. If in this process, these new technologies/approaches can be adopted to quantitatively assess ligament recovery under any of the existing rehabilitation programs, a new procedure may have emerged that is capable of delivering essential diagnostic and therapeutic information at significantly lower cost.
The novel process of the invention employs a modification of commercially available stress equipment used to assess trauma-induced laxity in a variety of joints including the ankle, knee, elbow and shoulder. Electronic sensors attached to the stress equipment measure the location of specific anatomical reference points. These measurements are used in mathematical models to calculate the percentage of remaining or regained function in the traumatized ligaments without the use of imaging modalities or invasive procedures.
Computer software presents the results and diagnosis in a clinical format. The examination is performed in a matter of minutes and at a fraction of the usual cost by a trained technician and does not require a hospital setting. The preferred embodiment of the assembled device is available in a lightweight briefcase-sized portable unit and can be operated wherever a PC or laptop is available.
The invention improves standard graded stress radiographic exams to eliminate the need for x-rays or other imaging modalities, and it makes ligament stress exams accessible to non-radiological personnel, such as athletic trainers, without loss in diagnostic accuracy.